Pre-cancerous cell changes sometimes 'hidden' in anal warts of gay men

Cancerous or “high-grade” pre-cancerous cells changes were detected in a high proportion of anal warts surgically removed from gay men, US investigators report in the July 1^st edition of Clinical Infectious Diseases.

The investigators believe that their findings could have implications for the management of anal warts.

There are two types of human papilloma virus (HPV) that can infect the anogenital tract. Strains of the virus that cause cauliflower-like anogential warts involve a low risk of anal cancer. However, some strains of the virus, especially HPV 16 and 18, can cause anal cancer and its precursor, the pre-cancerous cell changes called high-grade anal intraepithelial neoplasia (AIN).

Investigators wished to see if there was evidence of occult – or hidden – anal cancer or pre-cancerous cell changes in the anal warts which were surgically removed from 320 gay men, 50% of whom were HIV-positive.

All the removed tissue samples were sent to a laboratory to examine for cell changes.

The study was retrospective and involved patients who received treatment between 2002 and 2007.

Laboratory examination of the removed tissue showed that 34% of men had high-grade pre-cancerous cell changes (anal intraepithelial neoplasia grade 2 or 3).

Anal cancer was detected in 3% of men.

HIV-positive men were significantly more likely to have high-grade pre-cancerous cell changes than men who were HIV-negative (47% vs. 26%, p = 0.002).

Of the eight men with anal cancer, seven were HIV-positive.

Mean CD4 cell count amongst the patients with HIV was 431 cells/mm³, and 50% had an undetectable viral load.

Neither CD4 cell count nor viral load was associated with an increased risk of pre-cancerous cell changes.

However, CD4 cell counts were lower among the patients with anal cancer than other individuals (218 vs. 441 cells/mm³).

“Because anogential condylomata [warts] are classically associated with low-risk HPV types, the presence of high-grade anal intraepithelial neoplasia within what appears to be a low-grade condylomatous lesion [wart] is unsettling”, comment the investigators.

They add, “these data emphasize the importance of obtaining tissue for histopathological examination in men who have sex with men presenting for treatment of anogenital [warts].”